Large-scale columnar structure made of a fiber reinforced plastic

ABSTRACT

A large-sized columnar body made of a fiber reinforced plastics materials (FRP) has three layers A, B and C in this order, respectively formed by a fiber reinforced plastics material consisting of continuous fibers and a resin, wherein the reinforcing fibers of the layer B are carbon fibers arranged in the longitudinal direction of the columnar body and that the reinforcing fibers of the layers A and C are carbon fibers and/or glass fibers arranged at ±50 to ±70 degrees with respect to the longitudinal direction of the columnar body. The large-sized columnar body made of FRP has a high compressive strength and hence can be lighter than conventional large-sized columnar bodies. Hence, it is suitable as a primary structural member used in buildings, structural components, aircraft, ships, and the like.

This application is based on International Application No.PCT/JP97/01629, filed May 15, 1997.

TECHNICAL FIELD

The present invention relates to a large-sized columnar body made of afiber reinforced plastics material (hereunder abbreviated as FRP)consisting of reinforcing fibers and a resin, used as a primarystructural member in buildings, structural components, aircraft, ships,etc.

BACKGROUND ARTS

A large-sized columnar body typically used as a mast of a racing yachtis required to have light weight, high rigidity and high strength, forsecuring the high speed stability, maneuverability and safety of theboat. In addition, aerodynamically for the necessity of high airreleasability, a large-sized columnar body with a simple circular crosssection is insufficient, and a large-sized columnar body with anellipsoidal cross section or with a specific streamlined cross sectionselection of which is based on wind tunnel experiments is demanded.

A long and large columnar body generally called a pole must be taperedfor the necessity of weight balance in the longitudinal direction.

As large-sized columnar bodies to meet these demands, those made of FRPare attracting attention in recent years, and are proposed in (1)Japanese Patent Laid-Open (Kokai) No. 57-60989, (2) Japanese PatentLaid-Open (Kokai) No. 59-63289, (3) Japanese Patent Laid-Open (Kokai)No. 4-255306, etc.

(1) Japanese Patent Laid-Open (Kokai) No. 57-60989 discloses a techniqueto reinforce the rigidity of a mast of a sling boat by letting the masthave a reinforcing portion swelling outside at least in either bow orstern direction. Furthermore, the patent gazette discloses a structurein which layers oriented in directions of ±20 to ±70 degrees withrespect to the longitudinal axis of the mast are formed inside thereinforcing portion, for the purpose of improving the torsional rigidityof the mast.

(2) Japanese Patent Laid-Open (Kokai) No. 59-63289 discloses a mast madeof FRP for surfing with a hollow cylindrical structure in which anintermediate layer with glass fibers and reinforcing fibers with amodulus higher than that of glass fibers is held between layers withglass fibers as reinforcing fibers.

(3) Japanese Patent Laid-Open (Kokai) No. 4-255306 discloses alarge-sized columnar body in which two shells prepared by laying upunidirectional prepreg sheets consisting of carbon fibers and an epoxyresin are bonded in the longitudinal direction to form an integralstructure.

In the meantime, FRP is low in compressive strength as compared withtensile strength, unlike metallic materials, and for this reason, whenFRP is used as a large-sized columnar body, how to highly manifest thecompressive strength of FRP is a key issue to achieve weight reduction.In other words, in most cases, the compressive strength decides theweight of a large-sized columnar body.

While all of the above patent gazettes (1) to (3) relate to large-sizedcolumnar bodies made of FRP with light weight and high performance, thepatent gazette (3) only describes that it is desirable to let a layer of0 degree in fiber orientation degree account for 50% or more or, asrequired, to lay up a 45-degree layer or 90-degree layer in combination,as a means for improving the compressive strength of a large-sizedcolumnar body.

The object of the present invention is to provide a large-sized columnarbody made of FRP improved in compressive strength, and with lighterweight and higher safety.

DISCLOSURE OF THE INVENTION

The present invention relates to a large-sized columnar body made of afiber reinforced plastics material, which has three layers [A], [B] and[C] respectively formed by a fiber reinforced plastics materialconsisting of continuous fibers and a resin, characterized in that thereinforcing fibers of the layer [B] are carbon fibers arranged in thelongitudinal direction of the columnar body, and that the reinforcingfibers of the layers [A] and [C] are carbon fibers and/or glass fibersarranged at ±50 to ±70 degrees with respect to the longitudinaldirection of the columnar body.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic drawing showing an embodiment of the large-sizedcolumnar body made of a fiber reinforced plastics material of thepresent invention. 1 . . . large-sized columnar body 2 . . . layer [A] 3. . . layer [B] 4 . . . layer [C]

MOST PREFERRED EMBODIMENTS OF THE INVENTION

It is preferable that the large-sized columnar body of the presentinvention, as typically used as a mast of a yacht, has a length of about1 m to 20 m and a width or thickness (the diameter of the largestcircumscribed circle of cross section) of 30 mm to 1000 mm.

The cross sectional form of the large-sized columnar body can bevarious, for example, circular, ellipsoidal, triangular, oval or like astreamlined blade, and may have open holes and neck portions forconnecting other parts. It is preferable that the cross section ishollow.

The reinforcing fibers of the layer [B] must be continuous carbon fibersto keep the large-sized columnar body lighter in weight.

In general, as the carbon fibers, mainly PAN based carbon fibers madefrom polyacrylonitrile or pitch based carbon fibers are used. The carbonfibers in the present invention can be either PAN based carbon fibers orpitch based carbon fibers. It is preferable that the carbon fibers havea modulus of 200 GPa to 700 GPa and a strength of 1 GPa to 10 GPa. Thecontinuous fibers are usually long fibers with a fiber length of 1 m ormore.

The resins which can be used here include thermosetting resins such asepoxy resins, vinyl ester resins, unsaturated polyester resins, phenolresins, polyimide resins and polyurethane resins, thermoplastic resinssuch as polyethylene resins, nylon resins, polypropylene resins,polyamide resins, ABS resins, polybutylene terephthalate resins,polyacetal resins and polycarbonate resins, etc. For enhancing thecompressive strength of the large-sized columnar body, a resin with amodulus of 3 GPa or more is preferable. The modulus of a resin in thiscase is measured according to JIS K 7113.

When a large and long columnar body is used in contact with sea waterlike a mast of a sailing boat or yacht, etc., it is preferable to use avinyl ester resin or polyester resin excellent in corrosion resistance,or a resin mainly composed of it.

It is preferable that the weight fraction of the reinforcing carbonfibers in the resin is 45% to 85%, for more highly manifesting thestrength and modulus of the reinforcing fibers in the resin. If thefraction is less than 45%, the amount of resin is too much to obtain theeffect of weight reduction, and if more than 85%, the resin is notsufficiently diffused around the fibers, so that the stress transferefficiency between fibers is lowered. Having regard to processability,it is more preferable that the weight fraction of the reinforcing carbonfibers in the resin is 55% to 75%.

It is also preferable that the carbon fibers are treated on the surfacesor contain a sizing agent for better adhesion to the resin.

Ideally it is preferable that the continuous carbon fibers in the layer[B] are arranged in the longitudinal direction of the large-sizedcolumnar body, but actually if they are arranged within ±5 degrees withrespect to the longitudinal axis of the large-sized columnar body, thereis no problem.

If the large-sized columnar body is a mast of a sailing boat or yacht,it must have a certain rigidity for higher maneuverability. Hence, it ispreferable that the carbon fibers of the layer [B] have a modulus of 350GPa or more.

If the layer [B] is arranged more outwardly of the columnar body, thebending rigidity of the columnar body increases. If it is necessary tofurther enhance the bending rigidity, the cross sectional form of thecolumnar body can be modified as far as the aerodynamic drag, etc. arenot lowered. For example, the wall thickness can be increased toincrease the geometrical moment of inertia around the axis requiring therigidity, or as stated in Japanese Patent Laid-Open No. 57-60989,reinforcing protrusions can also be provided.

It is important that the [A] layer 2 and the [C] layer 4 exist insideand outside the [B] layer 3 respectively adjacently to the [B] layer 3.

The layers [A] and [C] contain continuous carbon fibers or glass fibers,and the fibers are arranged in directions of ±50 to ±70 degrees withrespect to the axis of the large-sized columnar body. This is intendedto support the layer [B] from both sides, to enhance the compressivestrength of the layer [B]. If the orientation angles are smaller than±50 degrees, delamination from the layer [B] occurs, and if larger than±70 degrees, the supporting layers must be thicker, to increase theweight of the large-sized columnar body. A more preferable angle rangeis ±55 to ±75 degrees, and the most preferable angles are about ±60degrees.

Japanese Patent Publication (Kokoku) No. 57-60989 discloses a techniquein which layers with fibers arranged in directions of ±20 to ±70 degreesare formed inside a reinforcing portion provided to swell in the bow orstem direction in a cylindrical mast for the purpose of improving thetorsional rigidity. In the present invention, the existence of thereinforcing portion is not necessarily required, and layers withcontinuous fibers arranged in directions of ±50 to ±70 degrees existinside and outside the 0-degree layer (layer [B] ), to enhance thecompressive strength of the 0-degree layer and furthermore to enhancethe compressive strength of the large-sized columnar body.

In the present invention, it is preferable that the thickness ratio ofthe layer [B] to the layer [A] ([B]:[A]) and the thickness ratio of thelayer [B] to the layer [C] ([B]:[C]) are 1:0.05 to 1:0.4. If the ratiois less than 1:0.05, the above mentioned effect of supporting the layer[B] is not remarkable, and if more than 1:0.4, the weight increases sothat the effect of reducing the weight of the large-sized columnar bodyis lowered, although the supporting effect is sufficient. Having regardto the balance between the supporting effect and the weight reductioneffect, it is preferable that [B]:[A] and [B]: and [C] are 1:0.1 to1:0.3. It is of course not necessary that the thickness of [A] is equalto that of [C], but having regard to symmetry, it is preferable thatboth the thicknesses are almost equal.

It is further more preferable that the layer [A] or [C] is a biaxiallyfiber oriented layer in which the same quantities of fibers are arrangedin the + direction and the - direction in the layer. For example, thelayer [A] or [C] can be a layer with respectively one or more prepregsheets arranged at ±θ(50 degrees≦θ≦70 degrees), or ±θ sheets (50degrees≦θ≦70 degrees) formed simultaneously by FW, or cloth sheetsarranged in two directions (directions of ±50 to ±70 degrees).

Therefore, strictly, each of the layer [A] and the layer [C] can be saidto be a mono-layer or multi-layer in which continuous reinforcing fibersare arranged within a range of ±50 degrees to ±70 degrees regularly orirregularly.

Of course the ±θ sheet and the -θ sheet of the multi-layer [A] and/orthe multi-layer [C] are not required to be equal in quantity, but havingregard to symmetry, it is preferable that the ±θ sheets are almost equalin quality.

If the large-sized columnar body is a mast of a sailing boat or yacht,it is effective that the orientation angle is ±50 to ±55 degrees forletting the layer [A] or [C] have the effect of enhancing the torsionalrigidity of the large-sized columnar body. It is more preferable thatwith the thickness ratio of the layer [A] or [C] kept small, forexample, ±45-degree sheets are provided adjacently to the layer [A] or[C], to enhance the torsional rigidity of the large-sized columnar body.

The reinforcing fibers of the layer [A] or [C] are carbon fibers orglass fibers. In the case of carbon fibers, PAN based or pitch basedcarbon fibers are preferable, as in the layer [B], and in the case of alarge-sized columnar body, carbon fibers with a modulus of 300 GPa ormore are preferable since the torsional rigidity of the large-sizedcolumnar body can be enhanced.

As the glass fibers, fibrous glass with silicon oxide (SiO₂) as the maincomponent such as E glass, C glass or S glass can be preferably used,and it is preferable that the fiber diameter is about 5 to 20 μm.Furthermore, in the present invention, E glass with higher universalityor S glass with higher strength is preferable. It is desirable that, asis also the case for carbon fibers, the glass fibers are treated on thesurfaces or contain a sizing agent for higher compatibility with theresin.

Japanese Patent Laid-Open (Kokai) No. 59-63289 discloses a mast forsurfing, in which both the inner and outer layers are formed by glassfibers while the intermediate layer is reinforced by combining glassfibers and fibers higher in modulus than glass fibers such as carbonfibers. According to the patent gazette, the intermediate layer containsglass fibers, and furthermore the fibers of the intermediate layer arearranged at 8 to 30 degrees. Hence, the technique is not sufficientlyable to enhance the compressive strength of a large-sized columnar body.Moreover, the glass fibers arranged on both sides of the intermediatelayer are used for keeping the bending rigidity of the mast lower thanthat achieved by using carbon fibers, but the layers [A] and [C] of thepresent invention are used for enhancing the compressive strength of thelayer [B] used as an intermediate layer.

Japanese Patent Laid-Open (Kokai) No. 4-255306 discloses a large-sizedcolumnar body, in which unidirectionally parallel prepreg sheetsconsisting of high performance carbon fibers and an epoxy resin, of 50to 70% in fiber content by volume and a ratio of 50% or more in fiberorientation of 0-degree are laminated and molded in the longitudinaldirection by an outer mold into two shells to be integrated into thecolumnar body by bonding in the longitudinal direction In the presentinvention, unlike the above technique, it is not necessary to split thecolumnar body into two shells to be integrated. On the contrary,splitting into two shells is not preferable since it cuts the fibers,thus remarkably lowering the compressive strength of the large-sizedcolumnar body. Furthermore, the patent gazette proposes the use of a0-degree layer and a 45-degree layer or 90-degree layer in combinationas a method for enhancing the compressive strength considered to beremarkably lowered by splitting into two shells. In addition, in thepresent invention, in addition to the layers [A] and [C] with fibersarranged in a range of ±50 to ±70 degrees, a 45-degree layer can be usedfor enhancing the torsional rigidity or a 90-degree layer can be usedfor enhancing the strength and rigidity in the diameter direction of thelarge-sized columnar body without any problem.

The present invention has been described, mainly considering theapplication as a mast of a sailing boat or yacht. However, the effect ofthe present invention can be manifested also as primary structuralmembers used in buildings (columns and poles of office buildings,dwelling houses, cottages, etc., supports of pedestals and benches,etc.), structural components (electric wire poles, street lamp poles,supports of signs, displays, guard rails, etc., shafts and shaft coversfor oil drilling, pipelines for transporting fluids such as oil and gas,poles of wind power generators, etc.), other poles (poles for sportssuch as volley ball and high jump), and aircraft, hulls, etc.

For forming into the large-sized columnar body of the present invention,any the publicly known forming method can be used. The forming methodswhich can be used here include, for example, filament winding (FW),sheet winding, sheet lay-up, sheet wrapping, tape winding, tapewrapping, hand lay-up, sheet molding process (SMC), stamping molding,resin injection, pultrusion, pull wind process, scrip process, etc. Inthe forming into the large-sized columnar body, it is preferable to formthe [A], [B] and [C] layers integrally all at once, but if it is thick,multi-step (sequential) forming can be effected. As a furtheralternative method, layers formed separately can be bonded.

EXAMPLE 1

Around a steel mandrel with a diameter of 70 mm, sixteen epoxy resinprepreg sheets (respectively with a thickness of 145 μm and an arealfiber unit weight of 150 g/m²) in which carbon fibers T700S (with anultimate strain of 2.0%, modulus of 230 GPa and diameter of 7 μm) madeby Toray Industries, Inc. were arranged in one direction were wound. Inthis case, the sixteen sheets were arranged, to specify from the mandrelside, as one sheet in 60-degree direction, one sheet in -60-degreedirection, twelve sheets in 0-degree direction, one sheet in -60-degreedirection and one sheet in 60-degree direction. They were hardened in anoven with 130° C. as the highest temperature for 2 hours, to obtain alarge-sized columnar body with a lay-up configuration of [60/-60/0₁₂/-60/60] and a wall thickness of 2.32 mm. The ratio of the ±60-degreesheets (on one side) to the 0-degree sheets was 0.17.

Both the ends of the large-sized columnar body were adhesively bonded tosteel cylinders, to conduct a compression test at a gauge length of 200mm. The compressive strength was as shown in Table 1.

EXAMPLE 2

A large-sized columnar body was obtained as described in Example 1,except that 50-degree sheets were used instead of the 60-degree sheetsand that -50-degree sheets were used instead of the -60-degree sheets.The result of a compression test conducted as described in Example 1 wasas shown in Table 1.

EXAMPLE 3

A large-sized columnar body was obtained as described in Example 1,except that 70-degree sheets were used instead of the 60-degree sheetsand that -70-degree sheets were used instead of the -60-degree sheets.The result of a compression test conducted as described in Example 1 wasas shown in Table 1.

EXAMPLE 4

A large-sized columnar body with a wall thickness of 2.90 mm wasobtained as described in Example 1, except that the lay-up configurationwas [(60)₂ /(-60)₂ /0₁₂ /(-60)₂ /(60)₂ ] formed by using four 60-degreesheets and four -60-degree sheets. The result of a compression testconducted as described in Example 1 was as shown in Table 1.

EXAMPLE 5

A large-sized columnar body with a wall thickness of 2.90 mm wasobtained as described in Example 1, except that the lay-up configurationwas [60/(-60)₃ /0₁₂ /(-60)₃ /60] formed by using two 60-degree sheetsand six -60-degree sheets. The result of a compression test conducted asdescribed in Example 1 was as shown in Table 1.

EXAMPLE 6

A large-sized columnar body with a wall thickness of 1.94 mm wasobtained as described in Example 1, except that the prepreg sheets usedfor the 60-degree sheets and -60-degree sheets respectively had athickness of 25 μm and an areal fiber unit weight of 25 g/m². The resultof a compression test conducted as described in Example 1 was as shownin Table 1.

EXAMPLE 7

A large-sized columnar body with a wall thickness of 2.08 mm wasobtained as described in Example 1, except that respectively two prepregsheets respectively with a thickness of 25 μm and an areal unit weightof 25 g/m² (four sheets in total) were used instead of the one 60-degreesheet and the one -60degree sheet corresponding to the layer [C]. Theresult of a compression test conducted as described in Example 1 was asshown in Table 1.

COMPARATIVE EXAMPLE 1

A large-sized columnar body was obtained as described in Example 6,except that 45-degree sheets were used instead of the 60-degree sheetsand that -45-degree sheets were used instead of the -60-degree sheets.The result of a compression test conducted as described in Example 6 wasas shown in Table 1.

COMPARATIVE EXAMPLE 2

A large-sized columnar body was obtained as described in Example 6,except that 85-degree sheets were used instead of the 60-degree sheetsand that -85-degree sheets were used instead of the -60-degree sheets.The result of a compression test conducted as described in Example 6 wasas shown in Table 1.

EXAMPLE 8

A large-sized columnar body with a wall thickness of 1.94 mm wasobtained as described in Example 1, except that the diameter of themandrel was 40 mm. The result of a compression test conducted asdescribed in Example 1 at a gauge length of 150 mm was as shown in Table2.

COMPARATIVE EXAMPLE 3

A large-sized columnar body with a wall thickness of 1.94 mm wasobtained as described in Example 8, except that 85-degree sheets wereused instead of the 60-degree sheets and that -85-degree sheets wereused instead of the -60-degree sheets. The result of a compression testconducted as described in Example 8 was as shown in Table 2.

EXAMPLE 9

Around a steel mandrel with a diameter of 70 mm, a strand (consisting of12000 filaments) of carbon fibers T700S (with an ultimate strain of2.0%, modulus of 230 GPa and diameter of 7 μm) produced by TorayIndustries, Inc. impregnated with phenol resin was wound in aconfiguration of [±60/±30/±60], and hardened in a 130° C. oven, toobtain a large-sized columnar body with a wall thickness of 2.32 mm. Theratio of the ±60-degree sheets (on one side) to the 0-degree sheets was0.15.

Both the ends of the large-sized columnar body were adhesively bonded tosteel cylinders, and a compression test was conducted at a gauge lengthof 200 mm. The compressive strength was as shown in Table 3.

EXAMPLE 10

A large-sized columnar body with a wall thickness of 2.46 mm wasobtained as described in Example 9, except that the ±60-degree sheetswere formed by a strand (consisting of 6900 filaments) of glass fibers(with a modulus of 70 GPa and diameter of 13 μm). The result of acompression test conducted as described in Example 9 was as shown inTable 3.

COMPARATIVE EXAMPLE 4

A large-sized columnar body with a wall thickness of 2.32 mm wasobtained as described in Example 9, except that ±88-degree sheets wereused instead of the ±60-degree sheets. The result of a compression testconducted as described in Example 9 was as shown in Table 3.

                  TABLE 1                                                         ______________________________________                                        Compression test results of sheet-wound large-sized columnar bodies           (with an inner diameter of 70 mm)                                              Orientation     Layer                                                        angle (degrees)  thickness ratio                                                                           Compressive load                                 [A]        [B]    [C]    [B]:[A]                                                                             [B]:[C]                                                                             kN                                       ______________________________________                                        Example 1                                                                             ±60 0      ±60                                                                             1:0.17                                                                              1:0.17                                                                              4.53                                   Example 2                                                                             ±50 0      ±50                                                                             1:0.17                                                                              1:0.17                                                                              4.30                                   Example 3                                                                             ±70 0      ±70                                                                             1:0.17                                                                              1:0.17                                                                              4.24                                   Example 4                                                                             ±60 0      ±60                                                                             1:0.33                                                                              1:0.33                                                                              4.58                                   Example 5                                                                             ±60 0      ±60                                                                             1:0.33                                                                              1:0.33                                                                              4.37                                   Example 6                                                                             ±60 0      ±60                                                                             1:0.06                                                                              1:0.06                                                                              4.14                                   Example 7                                                                             ±60 0      ±60                                                                             1:0.17                                                                              1:0.06                                                                              4.19                                   Comparative                                                                           ±45 0      +45  1:0.06                                                                              1:0.06                                                                              3.70                                   Example 1                                                                     Comparative                                                                           ±85 0      ±85                                                                             1:0.06                                                                              1:0.06                                                                              3.75                                   Example 2                                                                     ______________________________________                                    

                  TABLE 2                                                         ______________________________________                                        Compression test results of sheet-wound large-sized columnar bodies           (with an inner diameter of 40 mm)                                             Orientation      Layer                                                        angle (degrees)  thickness ratio                                                                           Compressive load                                 [A]        [B]    [C]    [B]:[A]                                                                             [B]:[C]                                                                             kN                                       ______________________________________                                        Example 8                                                                             ±60 0      ±60                                                                             1:0.17                                                                              1:0.17                                                                              3.50                                   Comparative                                                                           ±85 0      ±85                                                                             1:0.17                                                                              1:0.17                                                                              3.24                                   ______________________________________                                    

                  TABLE 3                                                         ______________________________________                                        Compression test results of filament-wound large-sized columnar               bodies (with an inner diameter of 70 mm)                                      Orientation      Layer                                                        angle (degrees)   thickness ratio                                                                          Compressive load                                 [A]        [B]    [C]    [B]:[A]                                                                             [B]:[C]                                                                             kN                                       ______________________________________                                        Example 9                                                                             ±60 ±3  ±60                                                                             1:0.15                                                                              1:0.15                                                                              4.35                                   Example 10                                                                            ±60 ±3  ±60                                                                             1:0.19                                                                              1:0.19                                                                              4.38                                   Comparative                                                                           ±88 ±3  ±88                                                                             1:0.15                                                                              1:0.15                                                                              4.01                                   ______________________________________                                    

INDUSTRIAL APPLICABILITY

As described above, the large-sized columnar body made of a fiberreinforced plastics material of the present invention has at least threeadjacent layers [A], [B] and [C] respectively formed by a fiberreinforced plastics material consisting of continuous reinforcing fibersand a resin. The reinforcing fibers of the layer [B] are carbon fibersarranged in the longitudinal direction of the columnar body, and thereinforcing fibers of the layers [A] and [C] are carbon fibers or glassfibers arranged at ±50 to ±70 degrees with respect to the longitudinaldirection of the columnar body. Thus, the large-sized columnar body hasa high compressive strength, and hence can have a weight lighter thanthose of conventional large-sized columnar bodies.

We claim:
 1. A large-sized columnar body made of a fiber reinforcedplastics material, comprising three layers A, B and C in this order,each layer being formed of a fiber reinforced plastics materialcomprising continuous fiber and a resin,wherein the reinforcing fibersof layer B consist of carbon fibers arranged in a longitudinal directionof the columnar body and the reinforcing fibers of layers A and C arecarbon fibers and/or glass fibers arranged at an angle of ±55 to ±65degrees with respect to the longitudinal direction of the columnar body,the thickness ratio of the layers A, B and C defined as the ratio A:B:Cis 0.05 to 0.4:1:0.05 to 0.4.
 2. A large-sized columnar body made of afiber reinforced plastics material, comprising three layers A, B and Cin this order, each layer being formed of a fiber reinforced plasticsmaterial comprising continuous fiber and a resin,wherein the reinforcingfibers of layer B consist of carbon fibers arranged in a longitudinaldirection of the columnar body and the reinforcing fibers of layers Aand C are carbon fibers and/or glass fibers arranged at an angle of ±50to ±70 degrees with respect to the longitudinal direction of thecolumnar body, the thickness ratio of the layers A, B and C defined asthe ratio A:B:C is 0.05 to 0.4:1:0.05 to 0.4.
 3. A large-sized columnarbody made of a fiber reinforced plastics material, comprising threelayers A, B and C in this order, each layer being formed of a fiberreinforced plastics material comprising continuous fiber and aresin,wherein the reinforcing fibers of layer B consist of carbon fibersarranged in a longitudinal direction of the columnar body and thereinforcing fibers of layers A and C are carbon fibers and/or glassfibers arranged at an angle of ±50 to ±70 degrees with respect to thelongitudinal direction of the columnar body, the thickness ratio of thelayers A, B and C defined as the ratio A:B:C is 0.1 to 0.3:1:0.1 to 0.3.4. A large-sized columnar body made of a fiber reinforced plasticsmaterial according to claim 2, wherein the reinforcing fibers of thelayers A and C are carbon fibers.
 5. A large-sized columnar body made ofa fiber reinforced plastics material according to claim 4, wherein thereinforcing fibers of the layers A, B and C have a weight fraction of 45to 85%.
 6. A large-sized columnar body made of a fiber reinforcedplastics material according to claim 4, wherein the weight fraction ofthe reinforcing fibers of the layers A, B and C is 55 to 75%.
 7. Alarge-sized columnar body made of a fiber reinforced plastics material,according to any one of claims 1, 2, 3 and 6, wherein the large-sizedcolumnar body is a mast of a yacht or sailing boat.
 8. A large-sizedcolumnar body made of a fiber reinforced plastics material, according toany one of claims 1 and 4-6, wherein the carbon fibers of the layer Bhave a modulus of 350 GPa or more and the reinforcing fibers of thelayers A and C are carbon fibers with a modulus of 300 GPa or more.
 9. Alarge-sized columnar body made of a fiber reinforced plastics materialaccording to claim 2, wherein the cross section is hollow.